1. Field
Example embodiments relate to an organic light emitting diode (OLED) display device having a reversed trapezoidal pixel defining layer to separate organic functional layers of adjacent pixels, thereby exhibiting excellent gradation characteristics and color purity, and to a method of fabricating the same.
2. Description of the Related Art
Generally, an OLED display device may emit light when electrons and holes injected into an emitting layer thereof through an electron injection electrode (cathode) and a hole injection electrode (anode), respectively, are combined. In particular, the holes and electrons may be combined in the emitting layer into excitons having an excited energy state, so when an energy level of the excitons is reduced to a ground state from the excited state, the OLED display device may emit light.
Accordingly, compared, e.g., to a conventional liquid crystal thin film display device, the OLED display device may not require a separate light source. Therefore, the OLED display device may have reduced volume and weight.
The OLED display devices may be classified into passive matrix types and active matrix types according to the driving method.
The passive-matrix OLED display device may have a simple configuration and, thus, may be fabricated in a simple process. The passive-matrix OLED display device, however, may have high consumption power, difficulty in fabricating a large-sized device, and a decreased aperture ratio as a number of interconnections therein increases. For example, while the passive-matrix OLED display device may be used for small display devices, the active-matrix OLED display device may be used for large display devices.
A conventional OLED display device may have an organic layer including an emitting layer between first and second electrodes. The organic layer may include an emitting layer and functional layers, e.g., a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer, to achieve an OLED display device having low resistance and high efficiency. However, the conventional functional layers of the organic layer, i.e., the hole injection layer, the hole transport layer, the electron transport layer and the electron injection layer, may be commonly formed on a conductive layer over all pixel regions in the OLED display device. Thus, charges may be laterally migrated, resulting in emitting light from undesired pixels and decreasing gradation characteristics and color purity of emitted red, green and blue lights, as well as white light created by mixing the red, green and blue lights.